I want to know if you can find out the level of the dungeons before going into it? I remember them telling us that you will be able to find out the level of the dungeon and determine if you should go into it. Or do we have to guess and get our asses kicked before we realize that the dungeon is obviously a higher level.

nobody can tell me?

If you get your ass handed to you its too hard. That's all I can tell you sorry

Read the sign on the door.

The dungeons level is dependent on your level when you first enter it, so if you enter it at level 1, then go back at level 80, you will face level 1 equivalent enemies.

There aren't levels for dungeons.

There's level scaling. You won't run into anything too much higher than yourself. Unless it's a quest dungeon with a pre-designated boss, of course. But those are very few.